Nanosized La0.7Sr0.3MnO3 perovskite has successfully synthesized via citrate method. The product was characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and particle size analyzer (PSA). The degradation of methyl orange (MO), as a model of organic pollutant, was investigated in aqueous suspensions of La0.7Sr0.3MnO3, as a visible-light photocatalyst, under a variety of conditions comprising amount of catalyst mass, pH of solution and the presence of electron acceptors of hydrogen peroxide, potassium persulphate, or hydrogen peroxide-urea. The MO was found to degrade more efficiently in acidic solution or in the presence of potassium persulphate as oxidant. The adsorption isotherm and the kinetic of photocatalytic degradation of MO were investigated. Reusability of the catalyst was also investigated. (C) 2014 Elsevier B.V. All rights reserved.